View Source Cldr.Print.Backend.Number (ex_cldr_print v1.0.1)
Formats numbers and currencies based upon CLDR's decimal formats specification.
The format specification is documentated in Unicode TR35.
There are several classes of formatting including non-scientific, scientific,
rules based (for spelling and ordinal formats), compact formats that display 1k
rather than 1,000 and so on. See Cldr.Number.to_string/2 for specific formatting
options.
non-scientific-notation-formatting
Non-Scientific Notation Formatting
The following description applies to formats that do not use scientific notation or significant digits:
If the number of actual integer digits exceeds the maximum integer digits, then only the least significant digits are shown. For example, 1997 is formatted as "97" if the maximum integer digits is set to 2.
If the number of actual integer digits is less than the minimum integer digits, then leading zeros are added. For example, 1997 is formatted as "01997" if the minimum integer digits is set to 5.
If the number of actual fraction digits exceeds the maximum fraction digits, then half-even rounding it performed to the maximum fraction digits. For example, 0.125 is formatted as "0.12" if the maximum fraction digits is 2. This behavior can be changed by specifying a rounding increment and a rounding mode.
If the number of actual fraction digits is less than the minimum fraction digits, then trailing zeros are added. For example, 0.125 is formatted as "0.1250" if the minimum fraction digits is set to 4.
Trailing fractional zeros are not displayed if they occur j positions after the decimal, where j is less than the maximum fraction digits. For example, 0.10004 is formatted as "0.1" if the maximum fraction digits is four or less.
scientific-notation-formatting
Scientific Notation Formatting
Numbers in scientific notation are expressed as the product of a mantissa and a power of ten, for example, 1234 can be expressed as 1.234 x 10^3. The mantissa is typically in the half-open interval [1.0, 10.0) or sometimes [0.0, 1.0), but it need not be. In a pattern, the exponent character immediately followed by one or more digit characters indicates scientific notation. Example: "0.###E0" formats the number 1234 as "1.234E3".
The number of digit characters after the exponent character gives the minimum exponent digit count. There is no maximum. Negative exponents are formatted using the localized minus sign, not the prefix and suffix from the pattern. This allows patterns such as "0.###E0 m/s". To prefix positive exponents with a localized plus sign, specify '+' between the exponent and the digits: "0.###E+0" will produce formats "1E+1", "1E+0", "1E-1", and so on. (In localized patterns, use the localized plus sign rather than '+'.)
The minimum number of integer digits is achieved by adjusting the exponent. Example: 0.00123 formatted with "00.###E0" yields "12.3E-4". This only happens if there is no maximum number of integer digits. If there is a maximum, then the minimum number of integer digits is fixed at one.
The maximum number of integer digits, if present, specifies the exponent grouping. The most common use of this is to generate engineering notation, in which the exponent is a multiple of three, for example, "##0.###E0". The number 12345 is formatted using "##0.####E0" as "12.345E3".
When using scientific notation, the formatter controls the digit counts using significant digits logic. The maximum number of significant digits limits the total number of integer and fraction digits that will be shown in the mantissa; it does not affect parsing. For example, 12345 formatted with "##0.##E0" is "12.3E3". Exponential patterns may not contain grouping separators.
significant-digits
Significant Digits
There are two ways of controlling how many digits are shows: (a) significant digits counts, or (b) integer and fraction digit counts. Integer and fraction digit counts are described above. When a formatter is using significant digits counts, it uses however many integer and fraction digits are required to display the specified number of significant digits. It may ignore min/max integer/fraction digits, or it may use them to the extent possible.
Link to this section Summary
Functions
Parse a string locale-aware manner and return a number.
Resolve curencies from strings within a list.
Resolve a currency from a string
Resolve and tokenize percent or permille from the beginning and/or the end of a string
Resolve and tokenize percent and permille sybols from strings within a list.
Scans a string locale-aware manner and returns a list of strings and numbers.
Formats a number and applies the :approximately format for
a locale and number system.
Formats a number and applies the :at_least format for
a locale and number system.
Formats a number and applies the :at_most format for
a locale and number system.
Formats the first and last numbers of a range and applies
the :range format for a locale and number system.
Returns a number formatted into a string according to a format pattern and options.
Same as the execution of to_string/2 but raises an exception if an error would be
returned.
Return a valid number system from a provided locale and number system name or type.
Link to this section Functions
Parse a string locale-aware manner and return a number.
arguments
Arguments
stringis anyString.toptionsis a keyword list of options
options
Options
:numberis one of:integer,:float,:decimalornil. The default isnilmeaning that the type auto-detected as either anintegeror afloat.:localeis any locale returned byCldr.Print.Backend.known_locale_names/0or aCldr.LanguageTag.t. The default isCldr.Print.Backend.get_locale/0.
returns
Returns
A number of the requested or default type or
{:error, {exception, error}}if no number could be determined
notes
Notes
This function parses a string to return a number but
in a locale-aware manner. It will normalise grouping
characters and decimal separators, different forms of
the + and - symbols that appear in Unicode and
strips any _ characters that might be used for
formatting in a string. It then parses the number
using the Elixir standard library functions.
examples
Examples
iex> Cldr.Print.Backend.Number.parse("+1.000,34", locale: "de")
{:ok, 1000.34}
iex> Cldr.Print.Backend.Number.parse("-1_000_000.34")
{:ok, -1000000.34}
iex> Cldr.Print.Backend.Number.parse("1.000", locale: "de", number: :integer)
{:ok, 1000}
iex> Cldr.Print.Backend.Number.parse("+1.000,34", locale: "de", number: :integer)
{:error,
{Cldr.Number.ParseError,
"The string \"+1.000,34\" could not be parsed as a number"}}
Resolve curencies from strings within a list.
arguments
Arguments
listis any list in which currency names and symbols are expectedoptionsis a keyword list of options
options
Options
:localeis any valid locale returned byCldr.known_locale_names/1or aCldr.LanguageTagstruct returned byCldr.Locale.new!/2The default isCldr.Print.Backend.get_locale():onlyis anatomor list ofatomsrepresenting the currencies or currency types to be considered for a match. The equates to a list of acceptable currencies for parsing. See the notes below for currency types.:exceptis anatomor list ofatomsrepresenting the currencies or currency types to be not considered for a match. This equates to a list of unacceptable currencies for parsing. See the notes below for currency types.:fuzzyis a float greater than0.0and less than or equal to1.0which is used as input toString.jaro_distance/2to determine is the provided currency string is close enough to a known currency string for it to identify definitively a currency code. It is recommended to use numbers greater than0.8in order to reduce false positives.
notes
Notes
The :only and :except options accept a list of
currency codes and/or currency types. The following
types are recognised.
If both :only and :except are specified,
the :except entries take priority - that means
any entries in :except are removed from the :only
entries.
:all, the default, considers all currencies:currentconsiders those currencies that have a:todate of nil and which also is a known ISO4217 currency:historicis the opposite of:current:tenderconsiders currencies that are legal tender:unannotatedconsiders currencies that don't have "(some string)" in their names. These are usually financial instruments.
examples
Examples
iex> Cldr.Print.Backend.Number.scan("100 US dollars")
...> |> Cldr.Print.Backend.Number.resolve_currencies
[100, :USD]
iex> Cldr.Print.Backend.Number.scan("100 eurosports")
...> |> Cldr.Print.Backend.Number.resolve_currencies(fuzzy: 0.75)
[100, :EUR]
iex> Cldr.Print.Backend.Number.scan("100 dollars des États-Unis")
...> |> Cldr.Print.Backend.Number.resolve_currencies(locale: "fr")
[100, :USD]
Resolve a currency from a string
arguments
Arguments
listis any list in which currency names and symbols are expectedoptionsis a keyword list of options
options
Options
:localeis any valid locale returned byCldr.known_locale_names/1or aCldr.LanguageTagstruct returned byCldr.Locale.new!/2The default isCldr.Print.Backend.get_locale():onlyis anatomor list ofatomsrepresenting the currencies or currency types to be considered for a match. The equates to a list of acceptable currencies for parsing. See the notes below for currency types.:exceptis anatomor list ofatomsrepresenting the currencies or currency types to be not considered for a match. This equates to a list of unacceptable currencies for parsing. See the notes below for currency types.:fuzzyis a float greater than0.0and less than or equal to1.0which is used as input toString.jaro_distance/2to determine is the provided currency string is close enough to a known currency string for it to identify definitively a currency code. It is recommended to use numbers greater than0.8in order to reduce false positives.
returns
Returns
An ISO4217 currency code as an atom or
{:error, {exception, message}}
notes
Notes
The :only and :except options accept a list of
currency codes and/or currency types. The following
types are recognised.
If both :only and :except are specified,
the :except entries take priority - that means
any entries in :except are removed from the :only
entries.
:all, the default, considers all currencies:currentconsiders those currencies that have a:todate of nil and which also is a known ISO4217 currency:historicis the opposite of:current:tenderconsiders currencies that are legal tender:unannotatedconsiders currencies that don't have "(some string)" in their names. These are usually financial instruments.
examples
Examples
iex> Cldr.Print.Backend.Number.resolve_currency("US dollars")
[:USD]
iex> Cldr.Print.Backend.Number.resolve_currency("100 eurosports", fuzzy: 0.75)
[:EUR]
iex> Cldr.Print.Backend.Number.resolve_currency("dollars des États-Unis", locale: "fr")
[:USD]
iex> Cldr.Print.Backend.Number.resolve_currency("not a known currency", locale: "fr")
{:error,
{Cldr.UnknownCurrencyError,
"The currency \"not a known currency\" is unknown or not supported"}}
@spec resolve_per(String.t(), Keyword.t()) :: Cldr.Number.Parser.per() | [Cldr.Number.Parser.per() | String.t()] | {:error, {module(), String.t()}}
Resolve and tokenize percent or permille from the beginning and/or the end of a string
arguments
Arguments
listis any list in which percent and permille symbols are expectedoptionsis a keyword list of options
options
Options
:localeis any valid locale returned byCldr.known_locale_names/1or aCldr.LanguageTagstruct returned byCldr.Locale.new!/2The default isoptions[:backend].get_locale()
returns
Returns
An
:percentorpermilleor{:error, {exception, message}}
examples
Examples
iex> Cldr.Print.Backend.Number.resolve_per "11%"
["11", :percent]
iex> Cldr.Print.Backend.Number.resolve_per "% of linguists"
[:percent, " of linguists"]
iex> Cldr.Print.Backend.Number.resolve_per "% of linguists %"
[:percent, " of linguists ", :percent]
@spec resolve_pers([String.t(), ...], Keyword.t()) :: [ Cldr.Number.Parser.per() | String.t() ]
Resolve and tokenize percent and permille sybols from strings within a list.
Percent and permille symbols can be identified at the beginning and/or the end of a string.
arguments
Arguments
listis any list in which percent and permille symbols are expectedoptionsis a keyword list of options
options
Options
:localeis any valid locale returned byCldr.known_locale_names/1or at:Cldr.LanguageTagstruct returned byCldr.Locale.new!/2The default isoptions[:backend].get_locale()
examples
Examples
iex> Cldr.Print.Backend.Number.scan("100%")
...> |> Cldr.Print.Backend.Number.resolve_pers()
[100, :percent]
Scans a string locale-aware manner and returns a list of strings and numbers.
arguments
Arguments
stringis anyString.toptionsis a keyword list of options
options
Options
:numberis one of:integer,:float,:decimalornil. The default isnilmeaning that the type auto-detected as either anintegeror afloat.:localeis any locale returned byCldr.known_locale_names/1or aCldr.LanguageTag.t. The default isCldr.Print.Backend.get_locale/0.
returns
Returns
- A list of strings and numbers
notes
Notes
Number parsing is performed by Cldr.Number.Parser.parse/2
and any options provided are passed to that function.
examples
Examples
iex> Cldr.Print.Backend.Number.scan("£1_000_000.34")
["£", 1000000.34]
iex> Cldr.Print.Backend.Number.scan("I want £1_000_000 dollars")
["I want £", 1000000, " dollars"]
iex> Cldr.Print.Backend.Number.scan("The prize is 23")
["The prize is ", 23]
iex> Cldr.Print.Backend.Number.scan("The lottery number is 23 for the next draw")
["The lottery number is ", 23, " for the next draw"]
iex> Cldr.Print.Backend.Number.scan("The loss is -1.000 euros", locale: "de", number: :integer)
["The loss is ", -1000, " euros"]
@spec to_approx_string(number() | Decimal.t(), Keyword.t() | Keyword.t() | map()) :: {:ok, String.t()} | {:error, {module(), String.t()}}
Formats a number and applies the :approximately format for
a locale and number system.
arguments
Arguments
numberis an integer, float or Decimal to be formattedoptionsis a keyword list defining how the number is to be formatted. SeeCldr.Number.to_string/3for a description of the available options.
example
Example
iex> Cldr.Print.Backend.Number.to_approx_string 1234
{:ok, "~1,234"}
@spec to_at_least_string(number() | Decimal.t(), Keyword.t() | Keyword.t() | map()) :: {:ok, String.t()} | {:error, {module(), String.t()}}
Formats a number and applies the :at_least format for
a locale and number system.
arguments
Arguments
numberis an integer, float or Decimal to be formattedoptionsis a keyword list defining how the number is to be formatted. SeeCldr.Print.Backend.Number.to_string/2for a description of the available options.
example
Example
iex> Cldr.Print.Backend.Number.to_at_least_string 1234
{:ok, "1,234+"}
@spec to_at_most_string(number() | Decimal.t(), Keyword.t() | Keyword.t() | map()) :: {:ok, String.t()} | {:error, {module(), String.t()}}
Formats a number and applies the :at_most format for
a locale and number system.
arguments
Arguments
numberis an integer, float or Decimal to be formattedoptionsis a keyword list defining how the number is to be formatted. SeeCldr.Number.to_string/3for a description of the available options.
example
Example
iex> Cldr.Print.Backend.Number.to_at_most_string 1234
{:ok, "≤1,234"}
@spec to_range_string(Range.t(), Keyword.t() | Keyword.t() | map()) :: {:ok, String.t()} | {:error, {module(), String.t()}}
Formats the first and last numbers of a range and applies
the :range format for a locale and number system.
arguments
Arguments
numberis an integer, float or Decimal to be formattedoptionsis a keyword list defining how the number is to be formatted. SeeCldr.Number.to_string/3for a description of the available options.
example
Example
iex> Cldr.Print.Backend.Number.to_range_string 1234..5678
{:ok, "1,234–5,678"}
@spec to_string(number() | Decimal.t(), Keyword.t() | map()) :: {:ok, String.t()} | {:error, {atom(), String.t()}}
Returns a number formatted into a string according to a format pattern and options.
arguments
Arguments
numberis an integer, float or Decimal to be formattedoptionsis a keyword list defining how the number is to be formatted.
options
Options
format: the format style or a format string defining how the number is formatted. SeeCldr.Number.Formatfor how format strings can be constructed. SeeCldr.Number.Format.format_styles_for/3to return available format styles for a locale. The defaultformatis:standard.If
:formatis set to:longor:shortthen the formatting depends on whether:currencyis specified. If not specified then the number is formatted as:decimal_longor:decimal_short. If:currencyis specified the number is formatted as:currency_longor:currency_shortand:fractional_digitsis set to 0 as a default.:formatmay also be a format defined by CLDR's Rules Based Number Formats (RBNF). Further information is found in the moduleCldr.Rbnf. The most commonly used formats in this category are to spell out the number in a the locales language. The applicable formats are:spellout,:spellout_year,:ordinal. A number can also be formatted as roman numbers by using the format:romanor:roman_lower.currency: is the currency for which the number is formatted. For available currencies seeCldr.Currency.known_currencies/0. This option is required if:formatis set to:currency. Ifcurrencyis set and no:formatis set,:formatwill be set to:currencyas well.currency_symbol: Allows overriding a currency symbol. The alternatives are::isothe ISO currency code will be used instead of the default currency symbol.:narrowuses the narrow symbol defined for the locale. The same narrow symbol can be defined for more than one currency and therefore this should be used with care. If no narrow symbol is defined, the standard symbol is used.:symboluses the standard symbol defined in CLDR. A symbol is unique for each currency and can be safely used.- "string" uses
stringas the currency symbol :standard(the default and recommended) uses the CLDR-defined symbol based upon the currency format for the locale.
:cash: a boolean which indicates whether a number being formatted as a:currencyis to be considered a cash value or not. Currencies can be rounded differently depending on whether:cashistrueorfalse. *This option is deprecated in favour ofcurrency_digits: :cash.:currency_digitsindicates which of the rounding and digits should be used. The options are:accountingwhich is the default,:cashor:iso:rounding_mode: determines how a number is rounded to meet the precision of the format requested. The available rounding modes are:down, :half_up, :half_even, :ceiling, :floor, :half_down, :up. The default is:half_even.:number_system: determines which of the number systems for a locale should be used to define the separators and digits for the formatted number. Ifnumber_systemis anatomthennumber_systemis interpreted as a number system. If the:number_systemisbinarythen it is interpreted as a number system name. SeeCldr.Number.System.number_system_names_for/2. The default is:default.:locale: determines the locale in which the number is formatted. SeeCldr.known_locale_names/0. The default isCldr.get_locale/0which is the locale currently in affect for thisProcessand which is set byCldr.put_locale/1.If
:fractional_digitsis set to a positive integer value then the number will be rounded to that number of digits and displayed accordingly - overriding settings that would be applied by default. For example, currencies have fractional digits defined reflecting each currencies minor unit. Setting:fractional_digitswill override that setting.If
:maximum_integer_digitsis set to a positive integer value then the number is left truncated before formatting. For example if the number1234is formatted with the optionmaximum_integer_digits: 2, the number is truncated to34and formatted.If
:round_nearestis set to a positive integer value then the number will be rounded to nearest increment of that value - overriding settings that would be applied by default.:minimum_grouping_digitsoverrides the CLDR definition of minimum grouping digits. For example in the localeesthe number1234is formatted by default as1345because the locale defines theminimium_grouping_digitsas2. Ifminimum_grouping_digits: 1is set as an option the number is formatting as1.345. The:minimum_grouping_digitsis added to the grouping defined by the number format. If the sum of these two digits is greater than the number of digits in the integer (or fractional) part of the number then no grouping is performed.:wrapperis a 2-arity function that will be called for each number component with parametersstringandtagwheretagis one of:number,:currency_symbol,:currency_space,:literal,:quote,:percent,:permille,:minusor:plus. The function must return a string. The function can be used to wrap format elements in HTML or other tags.
locale-extensions-affecting-formatting
Locale extensions affecting formatting
A locale identifier can specify options that affect number formatting. These options are:
nu: defines the number system to be used if none is specified by the:number_systemoption toto_string/2
This key is part of the u extension and that document should be consulted for details on how to construct a locale identifier with these extensions.
wrapping-format-elements
Wrapping format elements
Wrapping elements is particularly useful when formatting a number with a currency symbol and the requirement is to have different HTML formatting applied to the symbol than the number. For example:
iex> Cldr.Number.to_string(100, format: :currency, currency: :USD, wrapper: fn
...> string, :currency_symbol -> "<span class=\"symbol\">" <> string <> "</span>"
...> string, :number -> "<span class=\"number\">" <> string <> "</span>"
...> string, :currency_space -> "<span>" <> string <> "</span>"
...> string, _other -> string
...> end)
{:ok, "<span class=\"symbol\">$</span><span class=\"number\">100.00</span>"}It is also possible and recommended to use the Phoenix.HTML.Tag.content_tag/3
function if wrapping HTML tags since these will ensure HTML entities are
correctly encoded. For example:
iex> Cldr.Number.to_string(100, format: :currency, currency: :USD, wrapper: fn
...> string, :currency_symbol -> Phoenix.HTML.Tag.content_tag(:span, string, class: "symbol")
...> string, :number -> Phoenix.HTML.Tag.content_tag(:span, string, class: "number")
...> string, :currency_space -> Phoenix.HTML.Tag.content_tag(:span, string)
...> string, _other -> string
...> end)
{:ok, "<span class=\"symbol\">$</span><span class=\"number\">100.00</span>"}When formatting a number the format is parsed into format elements that might include
a currency symbol, a literal string, inserted text between a currency symbol and the
currency amount, a percent sign, the number itself and several other elements. In
some cases it is helpful to be apply specific formatting to each element.
This can be achieved by specifying a :wrapper option. This option takes a 2-arity
function as an argument. For each element of the format the wrapper function is called
with two parameters: the format element as a string and an atom representing the
element type. The wrapper function is required to return a string that is then
inserted in the final formatted number.
returns
Returns
{:ok, string}or{:error, {exception, message}}
examples
Examples
iex> Cldr.Print.Backend.Number.to_string 12345
{:ok, "12,345"}
iex> Cldr.Print.Backend.Number.to_string 12345, locale: "fr"
{:ok, "12 345"}
iex> Cldr.Print.Backend.Number.to_string 1345.32, currency: :EUR, locale: "es", minimum_grouping_digits: 1
{:ok, "1.345,32 €"}
iex> Cldr.Print.Backend.Number.to_string 1345.32, currency: :EUR, locale: "es"
{:ok, "1345,32 €"}
iex> Cldr.Print.Backend.Number.to_string 12345, locale: "fr", currency: "USD"
{:ok, "12 345,00 $US"}
iex> Cldr.Print.Backend.Number.to_string 12345, format: "#E0"
{:ok, "1.2345E4"}
iex> Cldr.Print.Backend.Number.to_string 12345, format: :accounting, currency: "THB"
{:ok, "THB 12,345.00"}
iex> Cldr.Print.Backend.Number.to_string -12345, format: :accounting, currency: "THB"
{:ok, "(THB 12,345.00)"}
iex> Cldr.Print.Backend.Number.to_string 12345, format: :accounting, currency: "THB",
...> locale: "th"
{:ok, "฿12,345.00"}
iex> Cldr.Print.Backend.Number.to_string 12345, format: :accounting, currency: "THB",
...> locale: "th", number_system: :native
{:ok, "฿๑๒,๓๔๕.๐๐"}
iex> Cldr.Print.Backend.Number.to_string 1244.30, format: :long
{:ok, "1 thousand"}
iex> Cldr.Print.Backend.Number.to_string 1244.30, format: :long, currency: "USD"
{:ok, "1,244 US dollars"}
iex> Cldr.Print.Backend.Number.to_string 1244.30, format: :short
{:ok, "1K"}
iex> Cldr.Print.Backend.Number.to_string 1244.30, format: :short, currency: "EUR"
{:ok, "€1K"}
iex> Cldr.Print.Backend.Number.to_string 1234, format: :spellout
{:ok, "one thousand two hundred thirty-four"}
iex> Cldr.Print.Backend.Number.to_string 1234, format: :spellout_verbose
{:ok, "one thousand two hundred and thirty-four"}
iex> Cldr.Print.Backend.Number.to_string 1989, format: :spellout_year
{:ok, "nineteen eighty-nine"}
iex> Cldr.Print.Backend.Number.to_string 123, format: :ordinal
{:ok, "123rd"}
iex> Cldr.Print.Backend.Number.to_string 123, format: :roman
{:ok, "CXXIII"}
iex> Cldr.Print.Backend.Number.to_string 123, locale: "th-u-nu-thai"
{:ok, "๑๒๓"}
errors
Errors
An error tuple {:error, reason} will be returned if an error is detected.
The two most likely causes of an error return are:
- A format cannot be compiled. In this case the error tuple will look like:
iex> Cldr.Print.Backend.Number.to_string(12345, format: "0#")
{:error, {Cldr.FormatCompileError,
"Decimal format compiler: syntax error before: \"#\""}}- The format style requested is not defined for the
localeandnumber_system. This happens typically when the number system is:algorithmicrather than the more common:numeric. In this case the error return looks like:
iex> Cldr.Print.Backend.Number.to_string(1234, locale: "he", number_system: "hebr")
{:error, {Cldr.UnknownFormatError,
"The locale :he with number system :hebr does not define a format :standard"}}
Same as the execution of to_string/2 but raises an exception if an error would be
returned.
arguments
Arguments
numberis an integer, float or Decimal to be formattedoptionsis a keyword list defining how the number is to be formatted. SeeCldr.Print.Backend.Number.to_string/2
returns
Returns
a formatted number as a string or
raises an exception
examples
Examples
iex> Cldr.Print.Backend.Number.to_string! 12345
"12,345"
iex> Cldr.Print.Backend.Number.to_string! 12345, locale: "fr"
"12 345"
@spec validate_number_system( Cldr.Locale.locale_name() | Cldr.LanguageTag.t(), Cldr.Number.System.system_name() | Cldr.Number.System.types() ) :: {:ok, Cldr.Number.System.system_name()} | {:error, {module(), String.t()}}
Return a valid number system from a provided locale and number system name or type.
The number system or number system type must be valid for the given locale. If a number system type is provided, the underlying number system is returned.
arguments
Arguments
localeis any valid locale name returned byCldr.known_locale_names/1or aCldr.LanguageTagstruct returned byCldr.Locale.new!/2system_nameis any number system name returned byCldr.known_number_systems/0or a number system type returned byCldr.known_number_system_types/0
examples
Examples
iex> Cldr.Print.Backend.Number.validate_number_system "en", :latn
{:ok, :latn}
iex> Cldr.Print.Backend.Number.validate_number_system "en", :default
{:ok, :latn}
iex> Cldr.Print.Backend.Number.validate_number_system "en", :unknown
{:error,
{Cldr.UnknownNumberSystemError, "The number system :unknown is unknown"}}
iex> Cldr.Print.Backend.Number.validate_number_system "zz", :default
{:error, {Cldr.InvalidLanguageError, "The language \"zz\" is invalid"}}